My bike has a very sturdy rear rack, bolted to the frame and supported by the rear axle. The rear wheel is steel and rated for 600 pounds. So I'm not worried too much about the weight. Are there other safety things I should be worried about (at low speeds)?

Racks sold in the US and on most bikes here are probably not designed with passengers in mind, yes. This rack is on a chinese built flying pigeon roadster, built for use there and in much of the third world. It's designers probably were considering passengers as a common use.

When I was a kid we would regularly ride two to a bike by having the passenger either sit on the cross bar, on the seat while the rider stood up in the pedals, as in Double Drunken Bike Riding - or on a luggage rack. I still occasionally see people sitting on the handlebars though I can't imagine how they do it.

Most rear racks have weigh ratings. My Blackburn which attaches to the frame eyelets is only rated for 50 pounds and I believe Tubus racks are rated to carry up 100 lbs. Those seat post mounted racks have a maximum load of about 25 lbs.

Here in New York City it's illegal to carry more people than the bike was designed to carry but, if you add some fold up BMX pegs, maybe a nice pillow to fit the rack, that might be a moot point. I can't remember ever seeing anyone ticketed for doubling.

"a passenger shall ride only upon or astride a permanent andregular seatattached to the bicycle or to a trailer towed by the bicycle"
Chapter 85, Section 11B 2(i):

I think you'd have a hard time equating a "rack" with a "regular seat" in that there is no actual seat on the rack, just a flat area intended for cargo. Even if it is commonly used as a seat in China, I don't think an American judge is gonna be persuaded, based on Chinese precedent, that the rack is a seat. Also, even if there is a rating on the rack of, say, 150 lb., and you passenger is less than that, there is a difference between static loads and live loads (i.e., people), and I know live load ratings for floors are lower than static load ratings for the same floors (need increased safety factors, etc).

__________________I stop for people / whose right of way I honor / but not for no one.

Originally Posted by bragi"However, it's never a good idea to overgeneralize."

FWIW, I wouldn't do it. Just because other people do something, that doesn't indicate that it is actually safe.

1) Even a pretty tough rack like an Old Man Mountain is only rated for 50-60 pounds. I can't imagine many out there will regularly hold 150+ lbs.
2) The passenger has a pretty tenuous setup; fairly easy to fall off.
3) Believe it or not, low impact falls can be more dangerous than some high-speed falls. At higher speeds you slide (assuming you don't slam straight into something); at slower speeds, you fall straight down and are more likely to break bones.
4) If the passenger starts to fall, and is holding onto you, they could easily drag you down with 'em.
5) I agree the cops won't bust you, but a rack is definitely not a seat. I'm reasonably certain that wording applies to child seats and child trailers.
6) I really can't imagine why it's necessary to begin with. Tell that lazy so-and-so to get their own bike.

I.e., if you want to carry passengers, maybe you ought to get a rickshaw.

FWIW, I wouldn't do it. Just because other people do something, that doesn't indicate that it is actually safe.

1) Even a pretty tough rack like an Old Man Mountain is only rated for 50-60 pounds. I can't imagine many out there will regularly hold 150+ lbs.
2) The passenger has a pretty tenuous setup; fairly easy to fall off.
3) Believe it or not, low impact falls can be more dangerous than some high-speed falls. At higher speeds you slide (assuming you don't slam straight into something); at slower speeds, you fall straight down and are more likely to break bones.
4) If the passenger starts to fall, and is holding onto you, they could easily drag you down with 'em.
5) I agree the cops won't bust you, but a rack is definitely not a seat. I'm reasonably certain that wording applies to child seats and child trailers.
6) I really can't imagine why it's necessary to begin with. Tell that lazy so-and-so to get their own bike.

I.e., if you want to carry passengers, maybe you ought to get a rickshaw.

Just so you know what I'm talking about:

1) I just looked at the Old Man Mountain racks. They're pretty puny. They attach with tiny little screws to fender eyelets and brake bosses. Even the version that attaches to the axle is no better, as it's basically their normal eyelet rack with an additional part to be supported by the axle. And so counter intuitively, the axle supported version is rated 10 pounds weaker than the normal version. I would not put a passenger on one of those.

The Old Man Mountain is not the sort of rack I'm talking about.

2) Do you mean by falling backwards? I don't know how likely this is, but it seems about the same as riding side saddle on anything else, which people have done successfully in many forms for years.

3) I grant you that falling is not pretty. If you do fall over backwards, you're basically falling three feet onto your head. On a hard surface. But I don't think it's likely.

4) As with 3. I wouldn't do this with someone who I didn't think could balance well.

5) I'm not sure on the wording. That's why I asked. But I don't see how it's definitely not a seat. Or, if it is definitely not a seat, how would it have to be different for you to consider it a seat? I could put a piece of plywood on it to flatten it, maybe put a cushion on it?

6) I also have trouble seeing it necessary. More that it's useful. If I have my bike (maybe I came from work) and meet up with someone who came somewhere on public transit, it would be easier to ride two on the bike than walk the bike.

Rickshaws are inferior for solo riding, which is most of the riding I do.

As far as the OP's rack goes, no, it's not a good idea. Xtracycle sells racks and parts with the intention of the occasional passenger, and I've always wondered about how the police might treat that. There have been reports of police stopping people for having extra passengers on this forum fairly recently.